There is an air damper proposed to obtain a large output with a compact size, and comprising a cylinder main member provided with two cylinder portions in juxtaposition; and a piston main member formed by a piston rod moving inside the two cylinder portions respectively (see Patent Document 1).
The air damper of the Patent Document 1 covers the whole braking force by a resistance due to a pressure change. In such a case, when the piston rod starts to move, the braking force is small, and when the operation advances, the braking force rapidly increases. Consequently, in such a method, in some cases, there may be caused situations wherein a braking object halts in a process of a movement, and moreover, starts to unexpectedly move backward toward a position before the movement from a middle of the movement so as to be difficult to properly control the movement of the aforementioned braking object in a whole process thereof. Also, in the air damper of the Patent Document 1, the braking force thereof depends on a cross-sectional area of the cylinder main member so as to have a limit for reducing a size thereof.